Method and Apparatus for Launching Objects in Dual Gradient Systems

ABSTRACT

An apparatus for launching objects, such as during casing cementing operations, in wells having dual gradient fluid systems or certain downhole internal diameter restrictions. A launching assembly is located below a dual gradient valve or other restriction. In one embodiment, control lines extend from the earth&#39;s surface to the launching assembly and control actuation of the launching assembly. In an alternative embodiment, a receptacle assembly is positioned above a dual gradient valve or other restriction, with control lines extending from the receptacle assembly to the launching assembly. A dart or other triggering object is launched from the earth&#39;s surface to the receptacle assembly in order to control actuation of the launching assembly.

CROSS REFERENCES TO RELATED APPLICATION

PRIORITY OF U.S. PROVISIONAL PATENT APPLICATION Ser. No. 61/640,802, FILED MAY 1, 2012, INCORPORATED HEREIN BY REFERENCE, IS HEREBY CLAIMED.

STATEMENTS AS TO THE RIGHTS TO THE INVENTION MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

NONE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a method and apparatus for selective launching of darts, balls or other objects in well bores. More particularly, the present invention pertains to a method and apparatus for selective launching of such darts, balls or other objects in wells equipped with dual gradient fluid systems or having other downhole internal diameter restrictions.

2. Brief Description of the Prior Art

Many offshore wells, and particularly those in deep water environments, are drilled using moveable drilling rigs such as drill ships, semi-submersible rigs and jack-up rigs before a permanent platform or other production facility is ever installed. Drilling operations conducted from such moveable drilling rigs differ from operations conducted from platform-supported drilling rigs in many respects. One such important difference is the location of the blowout preventor and wellhead assemblies.

When drilling from floating drilling rigs, blowout preventor and wellhead assemblies are not located on such rigs, but rather at or near the sea floor. A large diameter, relatively flexible pipe known as a riser serves as a conduit to connect the offshore rig to subsea blowout preventor and wellhead assemblies and, ultimately, the well below. During drilling operations, drill pipe and other downhole equipment is lowered from the rig through the riser, the subsea blowout preventor and wellhead assemblies, and into the well bore which extends into the earth's crust below.

Once a well has been drilled to a desired depth, large diameter pipe called casing is frequently installed in the well and cemented in place. Such casing is typically installed to provide structural integrity to the well-bore and keep geologic formations isolated from one another. The lower portion of each casing string is typically cemented in place, while the top end of each casing string is seated and secured within a subsea wellhead assembly.

When running casing, individual sections of pipe are inserted into a well-bore and joined together at the drilling rig using threaded connections until the casing reaches a desired length. After the final section of casing has been added, the entire length of casing, commonly referred to as a “casing string,” must typically be conveyed into a desired position within the well-bore, such that the upper portion of the casing string is seated within the subsea wellhead assembly.

After the casing has been landed in a desired position within a well, cement is pumped down the internal diameter of the casing, out the bottom or distal end of the casing and into the annular space formed between the outer surface of the casing and the inner wall of the well bore. During such cementing operations, it is frequently beneficial to launch certain pump-able objects—such as darts, plugs, balls or other objects—into the cement being pumped into the well. These pump-able objects are typically constructed of rubber or other material having similar properties and characteristics, and are used to wipe the internal diameter of the casing string while maintaining separation of the cement and the mud during cementing operations.

In many instances, such darts, balls, plugs and/or other objects (sometimes collectively referred to herein as “pump-able objects”) are suspended within a cementing head until the objects are released or “launched” at desired points during the cement pumping process. Such darts, balls, plugs and/or other objects should be beneficially held in place within the slurry flow passing through the cement head prior to being launched or released without being damaged or washed away by such slurry flow. Once released, such pump-able objects join the cement slurry flow and can be pumped down hole directly into a well.

During conventional cementing operations (such as, for example, wells equipped with conventional single-gradient fluid systems), such pump-able objects are typically held in a cement head or other similar apparatus at or near a drilling rig. After being launched, said pump-able objects can progress substantially the entire length of the casing and/or any landing string though the unrestricted internal bores of such tubular goods.

However, in certain circumstances (such as, for example, on subsea wells utilizing a dual gradient fluid system where the drilling riser is displaced with seawater or other relatively light-weight fluid), a special valve known as a drill string valve or dual gradient valve (“DGV”) is installed above the casing or liner to be cemented. Such DGV's permit one-directional flow through said DGV's (typically in a downward direction) while creating a significant restriction into the internal diameter of such casing or liner to be cemented.

As a result of the restriction caused by the DGV, darts, balls, plugs and/or other objects cannot pass through such DGV's. As a result, conventional plug dropping cement heads positioned at or above a rig floor cannot be used in connection with dual gradient fluid systems and/or wells equipped with DGV's.

Thus, there is a need for an apparatus that can be used in a well having a dual gradient fluid system, or a restriction in the flow bore of a well (including, without limitation, a DGV), to release at least one plug, dart, ball or other object into said well. Said apparatus should also be beneficially capable of operating other tool or assemblies situated below said DGV or other restriction.

SUMMARY OF THE INVENTION

The present invention comprises an apparatus for staging and launching darts, balls, plugs and/or other objects including, without limitation, pump-able objects used during casing cementing operations. The apparatus of the present invention can function in subsea drilling applications including, without limitation, in wells having dual gradient fluid systems and/or equipped with a DGV.

In a preferred embodiment, the present invention utilizes a receptacle device positioned above the DGV to receive a ball, dart or other object, and to transmit a hydraulic or other signal to a releasing device situated below said DGV. A ball, dart or other triggering object is dropped from a drilling rig, and seats within said receptacle device. Application of fluid pressure from above causes a sliding sleeve mechanism within said receptacle device to shift, thereby exposing at least one control line to fluid pressure. In this manner, such fluid pressure is transmitted through said control line to a launching device disposed below said DGV in order to actuate said launching device.

It is to be observed that said signal can also be conveyed via means other than hydraulic fluid pressure. For example, said signal can be transmitted mechanically, electrically or in another manner, or some combination thereof, without departing from the scope of the present invention.

In an alternative embodiment, the present invention also provides a means for controlling the launching of balls, plugs, darts or other objects from a downhole launching device using at least one control line extending from a rig. Such control line(s) can be connected to a swivel mechanism (such as, for example, the swivel disclosed in pending U.S. non-provisional patent application bearing Ser. No. 12/657,558, which is incorporated by reference herein for all purposes) at the surface that permits a pipe string to be rotated during cementing operations, but which still permits the launching device to function downhole with hydraulic pressure pumped from the drilling rig via such control line(s).

BRIEF DESCRIPTION OF DRAWINGS/FIGURES

The foregoing summary, as well as any detailed description of the preferred embodiments, is better understood when read in conjunction with the drawings and figures contained herein. For the purpose of illustrating the invention, the drawings and figures show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed in such drawings or figures.

FIG. 1 depicts a side view of a floating drilling rig vessel, such as a vessel that could be used to drill a well using a dual gradient fluid system.

FIG. 2 depicts a side partial sectional view of a remotely actuated launching assembly of the present invention disposed within certain subsea components of a well.

FIG. 3 depicts a side, partial sectional view of a first embodiment launching assembly of the present invention.

FIG. 4 depicts a side, partial sectional view of said first embodiment launching assembly of the present invention after a first dart has been launched.

FIG. 5 depicts a side, partial sectional view of said first embodiment launching assembly of the present invention after a second dart has been launched.

FIG. 6 depicts a side, partial sectional view of an alternative launching assembly of the present invention.

FIG. 7 depicts a side, partial sectional view of certain downhole components of said alternative launching assembly of the present invention.

FIG. 8 depicts a side, partial sectional view of certain downhole components of said alternative launching assembly of the present invention after a first dart has been launched.

FIG. 9 depicts a side, partial sectional view of certain downhole components of said alternative launching assembly of the present invention.

FIG. 10 depicts a side, partial sectional view of certain downhole components of said alternative launching assembly of the present invention after a second dart has been launched.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 depicts a side view of a floating drilling rig vessel 100 which floats on or near water surface 200. Said floating drilling vessel 100 generally comprises underwater substructure 101 and upper work support section 105 which extends above water surface 200. Derrick 102 extends upward from said upper work support section 105 and is generally disposed over rig floor 103. Riser assembly 104 comprises a tubular conduit that extends from floating drilling rig vessel 100 to subsea assemblies situated at or on the sea floor (not depicted in FIG. 1).

FIG. 2 depicts a side partial sectional view of a remotely actuated launching assembly 10 of the present invention disposed within certain subsea components of a well. Specifically, subsea wellhead assembly 108 and subsea BOP assembly 109 are disposed on sea floor 300, and provide access into a length of wellbore 111 previously drilled into the earth's crust. Riser 104 extends from said BOP assembly to floating drilling rig 100 (not shown in FIG. 2) situated on the water surface.

Still referring to FIG. 2, remotely actuated launching assembly 10 can be conveyed into riser 104 on landing string 110. Landing string 110, in turn, is used to land casing string 106 within a subterranean portion of said wellbore 111 in a manner well known to those having skill in the art. Float collar assembly 107 is disposed within said casing string 106 at or near the distal end of the casing string 106.

FIG. 3 depicts a side, partial sectional view of launching assembly 10 of the present invention. Subsea wellhead assembly 108 and subsea BOP assembly 109 are disposed on sea floor 300, and provide access into the upper opening of wellbore 111 previously drilled into the earth's crust. Riser 104 extends from said BOP assembly to floating drilling rig 100 (not shown in FIG. 3) situated on the water surface.

Remotely actuated launching assembly 10 is conveyed into riser 104 via landing string 110. Casing 106 is connected to casing hanger 112 which is depicted as landed within wellhead assembly 108. A plug staging assembly having wiper plugs 113 and 114 is disposed below said casing hanger 112.

Still referring to FIG. 3, remotely actuated launching assembly 10 of present invention is situated below dual gradient valve (“DGV”) 150. Said DGV 150 and launching assembly 10 permit cement and/or other fluid to flow through such components and into a wellbore below. Remotely actuated launching assembly 10 of the present invention also permits the use of darts, setting plugs, balls, wipers and/or other objects which can be held in place within said remotely actuating assembly 10 without being damaged or washed away by cement slurry flow, but which can be selectively launched or released into said slurry flow at desired points during the cementing process.

Remotely actuated launching assembly 10 generally comprises a central body member having a longitudinal bore extending though said central body member. At least one cage assembly is disposed within said longitudinal bore, and at least one dart or other launch-able object is mounted within said cage assembly; as depicted in FIG. 3, darts 120 and 121 are depicted as being loaded within axially stacked cage assemblies. Cement slurry can be pumped into said remotely actuated launching assembly 10 via an inlet port, into said central bore, past said cage assemblies, and, ultimately, into casing string 106 situated there-below. Objects held within said at least one cage assembly, such as a darts 120 and 121 or other launch-able object(s), can be selectively released into such cement slurry and the well below.

At least one pin puller assembly is provided for each cage assembly. As depicted in FIG. 3, remotely actuated launching assembly 10 is equipped with pin puller assemblies 11 and 12. Each of said pin puller assemblies 11 and 12 comprise a side-entry motorized assembly that is used to suspend darts (such as darts 120 and 121, respectively) on a hinged door until such time as release of said darts is desired. Said pin puller assemblies 11 and 12 are motorized assemblies equipped with fluid actuated motors well known to those having skill in the art. When launching of a dart is desired, motors of pin puller assemblies 11 and/or 12 are selectively actuated using fluid pressure to selectively open said hinged door(s) and allow passage of suspended objects.

Still referring to FIG. 3, hydraulic control lines 13 and 14 (such as, for example, ¼″ stainless steel tubing) extend from a surface facility (such as floating drilling vessel 100, not pictured in FIG. 3) through riser 104 to motorized pin puller assemblies 11 and 12, respectively. Hydraulic power control unit 16 is connected to said control lines 13 and 14, and provides power for actuating motorized pin puller assemblies 11 and 12. Control lines 13 and 14 can be connected to a swivel mechanism (such as, for example, the swivel disclosed in pending U.S. non-provisional patent application bearing Ser. No. 12/657,558, which is incorporated by reference herein for all purposes) that permits landing string 110 to be rotated during cementing operations, while still permitting remotely actuated launching assembly 10 to function downhole via hydraulic pressure conveyed through control lines 13 and 14.

FIG. 4 depicts a side, partial sectional view of launching assembly 10 of the present invention after a first dart 121 has been launched. Hydraulic fluid pressure supplied by hydraulic power control unit 16 is transmitted through control line 14 from a surface facility (such as floating drilling vessel 100, not pictured in FIG. 4) past DGV 150 to lower motorized pin puller assembly 12. Such fluid pressure transmitted via control line 14 permits actuation of lower motorized pin puller assembly 12, resulting in launching of dart 121 from launching assembly 10.

Although different well configurations are possible without departing from the scope of the present invention, as depicted in FIG. 4, first dart 121 is received within wiper plug member 114. Said first dart 121 can be coupled with said wiper plug member 114, which can be pumped downhole through the inner through bore of casing string 106.

FIG. 5 depicts a side, partial sectional view of launching assembly 10 of the present invention after a second dart 120 has been launched. Hydraulic fluid pressure supplied by hydraulic power control unit 16 is transmitted through control line 13 from a surface facility (such as floating drilling vessel 100, not pictured in FIG. 5) past DGV 150 to upper motorized pin puller assembly 11. Such fluid pressure transmitted via control line 13 permits actuation of upper motorized pin puller assembly 11, resulting in launching of dart 120 from launching assembly 10.

Although different well configurations are possible without departing from the scope of the invention, as depicted in FIG. 5, second dart 120 can be received within wiper plug member 113; wiper plug member 114 having already been launched as set forth above. Said second dart 120 can be coupled with said wiper plug member 113 and pumped downhole through the inner through bore of casing string 106.

FIG. 6 depicts a side, partial sectional view of an alternative launching assembly 10 of the present invention. As discussed above, remotely actuated launching assembly 10 is conveyed into riser 104 on landing string 110. Casing 106 is connected to casing hanger 112 which is depicted as landed within wellhead assembly 108. Plug staging assembly having wiper plugs 113 and 114 is disposed below said casing hanger 112.

Still referring to FIG. 6, remotely actuated launching assembly 10 of present invention is situated below DGV 150. As noted herein, said DGV 150 and launching assembly 10 permit cement and/or other fluid to flow through such components and into a wellbore below. Remotely actuated launching assembly 10 of the present invention also permits the use of darts, setting plugs, balls, wipers and/or other objects which can be held in place within the launching assembly 10 without being damaged or washed away by cement slurry flow, but which can be selectively launched or released into said slurry flow at desired points during the cementing process.

Still referring to FIG. 6, in a preferred embodiment, the present invention utilizes a receiving or receptacle assembly 20 positioned above DGV 150 to receive a ball, dart or other triggering object, and to transmit a hydraulic signal to remote launching assembly 10 situated below the DGV. A plug dropping cement head assembly 30 is positioned at or near the rig floor of a drilling rig vessel. When desired, a ball, dart or other triggering object is selectively launched from said plug dropping cement head assembly 30 at said drilling rig, and seats within said receptacle assembly 20.

Said receptacle assembly has a central through-bore and a sliding sleeve assembly defining first and second positions. In said first position, said central through bore is isolated from fluid communication with said at least one control line. In said second position (that is, after said sliding sleeve has been shifted), said through bore and said at least one control line are in fluid communication with one another.

Following the seating of such ball, dart or other triggering object within said receptacle assembly 20, application of fluid pressure from above causes at least one sliding sleeve mechanism within said receptacle assembly 20 to shift, thereby exposing at least one control line (extending from said receptacle assembly 20 to said remotely actuated launching assembly 10) to such fluid pressure. In this manner, such fluid pressure is transmitted through said control line to said remotely actuated launching assembly 10 disposed below DGV 150 in order to actuate said launching assembly.

It is to be observed that said signal can also be conveyed via means other than hydraulic fluid pressure. For example, said signal can be transmitted mechanically, electrically or in another manner, or some combination thereof, without departing from the scope of the present invention.

Referring to FIG. 7, hydraulic control lines 23 and 24 (such as, for example, ¼″ stainless steel tubing) extend from receptacle assembly 20 to motorized pin puller assemblies 12 and 11, respectively. First dart 121 and second dart 120 are loaded within said launching assembly 10.

When desired, a first triggering object 31 is launched from said plug dropping cement head assembly 30 positioned at or near a rig floor (such as, for example, rig floor 103 depicted in FIG. 1), and seats within a first sliding sleeve assembly within said receptacle assembly 20. Following the seating of such triggering object 31 within said receptacle assembly 20, application of fluid pressure from above causes said first sliding sleeve assembly within said receptacle device 20 to shift, thereby exposing control line 23 extending from such receptacle assembly 20 to said remotely actuated launching assembly 10 to such fluid pressure.

FIG. 8 depicts a side, partial sectional view of said alternative launching assembly 10 of the present invention. Fluid pressure is transmitted through control line 23 past DGV 150 to lower motorized pin puller assembly 12 of launching assembly 10. Such fluid pressure transmitted via control line 23 permits actuation of lower motorized pin puller assembly 12, resulting in launching of first dart 121 from launching assembly 10.

Although different well configurations are possible without departing from the scope of the invention, as depicted in FIG. 8, first dart 121 is received within wiper plug member 114. Said first dart 121 can be coupled with said wiper plug member 114 and pumped downhole through the inner through bore of casing string 106.

Referring to FIG. 9, when desired, a second triggering object 32 can be launched from said surface plug dropping cement head assembly 30, and seats within a second sliding sleeve assembly within said receptacle assembly 20. Following the seating of such second triggering object 32 within said receptacle assembly 20, application of fluid pressure from above causes a second sliding sleeve assembly within said receptacle assembly 20 to shift, thereby exposing control line 24 to such fluid pressure. Such hydraulic fluid pressure is transmitted through control line 24 past DGV 150 to upper motorized pin puller assembly 11.

FIG. 10 depicts a side, partial sectional view of said alternative launching assembly 10 of the present invention. Such fluid pressure transmitted via control line 24 permits actuation of upper motorized pin puller assembly 11, resulting in launching of second dart 120 from launching assembly 10. Although different well configurations are possible without departing from the scope of the invention, second dart 120 can be received within wiper plug member 113 (wiper plug member 114 having already been launched as set forth above). Said second dart 120 can be coupled with said wiper plug member 113 and pumped downhole through the inner through bore of casing string 106.

The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention. 

What is claimed:
 1. An apparatus for launching an object within a wellbore having a dual gradient fluid system and equipped with a dual gradient valve comprising: a) an automated launching assembly disposed below said dual gradient valve; and b) at least one control line extending from said launching assembly to a triggering assembly situated above said dual gradient valve.
 2. The apparatus of claim 1, wherein said triggering assembly is situated on a drilling rig.
 3. The apparatus of claim 2, wherein said triggering assembly further comprises: a) a hydraulic power source; and b) a hydraulic swivel assembly having an input and an output, wherein said input is in fluid communication with said power source and said output is in fluid communication with said at least one control line.
 4. The apparatus of claim 1, wherein said triggering assembly comprises a receptacle assembly disposed within said wellbore above said dual gradient valve, having a central through bore and at least one sliding sleeve adapted to receive a triggering object.
 5. The apparatus of claim 4, wherein said sliding sleeve defines a first position and a second position, said central through bore is isolated from fluid communication with said at least one control line in said first position, and said central through bore and said at least one control line are in fluid communication in said second position.
 6. The apparatus of claim 1, wherein said automated launching assembly further comprises: a) at least one cage assembly for receiving a launch-able object; b) a hinged door disposed under said launch-able object; and c) at least one actuator for selectively opening said hinged door.
 7. The apparatus of claim 6, wherein said at least one actuator comprises a motorized pin puller.
 8. A method for launching an object within a wellbore having a dual gradient fluid system and equipped with a dual gradient valve comprising: a) loading at least one launch-able object within a launching assembly; b) installing said launching assembly below said dual gradient valve; and c) triggering launch of said launch-able object from above said dual gradient valve.
 9. The method of claim 8, wherein said launching assembly further comprises: a) at least one cage assembly for receiving a launch-able object; b) a hinged door disposed under said launch-able object; and c) at least one actuator for selectively opening said hinged door.
 10. The method of claim 9, wherein said at least one actuator comprises a motorized pin puller.
 11. The method of claim 8, further comprising the step of installing at least one control line from said launching assembly to a drilling rig.
 12. The method of claim 11, further comprising the step of supplying hydraulic pressure through said at least one control line to actuate said launching assembly.
 13. The method of claim 12, wherein said hydraulic pressure is supplied from a hydraulic power unit situated at said drilling rig.
 14. The method of claim 8, further comprising installing at least one control line from said launching assembly to a receptacle assembly disposed within said wellbore above said dual gradient valve.
 15. The method of claim 14, wherein said receptacle assembly comprises a central through bore and at least one sliding sleeve.
 16. The method of claim 15, wherein said sliding sleeve defines a first position and a second position, said central through bore is isolated from fluid communication with said at least one control line in said first position, and said central through bore and said at least one control line are in fluid communication in said second position.
 17. The method of claim 16, wherein said step of triggering launch of said launch-able object from above said dual gradient valve further comprises shifting said sliding sleeve from said first position to said second position.
 18. The method of claim 17, wherein said step of shifting said sliding sleeve from said first position to said second position further comprises: a) launching a trigger object from a drilling rig; b) seating said trigger object in said receptacle assembly; and c) applying fluid pressure to said central through-bore of said receptacle assembly. 